Friedreigh's ataxia (FRDA) is the most common autosomal recessive neurodegenerative disease among Caucasian populations. FRDA is characterized by the early onset of the disease usually before the age of 25, a progressive ataxia, sensory loss, absence of tendon reflexes and pyramidal weakness of the legs (Friedreich N, Virchows Arch. Pathol. Anat., 68, 145–245 (1876); Freidreich N, Virchows Arch. Pathol. Anat., 70, 140–142 (1877); Harding, A. E., Brain 104, 589–620 (1981); Durr, A. et al., N Engl J Med 335, 1169–75 (1996)). FRDA is known to be caused by a mutation of a gene on chromosome 9q13.
The inventor has recently identified a patient group which is characterized by autosomal recessive inheritance, early age of onset, FRDA-like clinical presentations, and hypoalbuminemia. Linkage of a causative gene of this disease to the FRDA locus was excluded by linkage analysis.
The clinical presentations of this disease were similar to those of a disease, which is called “ataxia with oculmotor aprataxia, AOA” linked to 9p13 (do Ceu Moreira, M et al., Am J Hum Genet 68, 501–8 (2001)).
The causative gene for the disease, which the inventor has found has not yet been identified. Therefore, diagnosis of this disease has been based only on clinical observations.